The story of Shakambari Devi and Demon Durgamma is found in the Sri Devi Bhagavatam and Chandi Saptashati. The story is that an asura named Durgamma did tapas for 1,000 years to get a boon from Brahma by which he appropriated all the Vedic powers and knowledge of Vedas and sages.
As a result, all yajnas, pujas, chanting of Vedic hymns ground to a halt. On account of the reign of terror unleashed by the arrogant Durgamma, water sources dried up leading to severe famine on earth for 100 years.
All living beings including sages, humans, gods and goddesses realized that only Mother Goddess Shakti could save them and prayed to her for deliverance from misery and suffering.
The ever benevolent and compassionate Goddess Durga appeared as Shakambari Devi and created water and vegetables and fruits form her body for the hungry and thirsty living beings.
She also caused rains to facilitate good crops and harvest. She then killed Durgamma and rid the world of his menace.
Goddess Durga has since been worshipped with vegetables, green leaves and fruits.
Shakambari Devi is worshipped with fruits, vegetables and green leaves in many temples in South India including the famous Kanaka Durga Temple in Vijayawada and at Warangal Bhadrakali Temple. It is an important festival for the Telugu speaking people in Telangana, Andhra Pradesh, and in other parts of India and world.